package junit;

import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import org.springframework.util.Base64Utils;

/**
 * 签名 RSASignature
 * 
 * @author suns suntion@yeah.net
 * @since 2017年4月6日下午4:34:15
 */
public class RsaSignature {
    /**
     * 签名算法
     */
    public static final String SIGN_ALGORITHMS = "SHA1WithRSA";

    /**
     * RSA签名
     * @param content
     *            待签名数据
     * @param privateKey
     *            商户私钥
     * @param encode
     *            字符集编码
     * @return 签名值
     * @throws Exception 
     */
    public static String sign(String content, String privateKey, String encode) throws Exception {
        try {
            PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(Base64Utils.decodeFromString(privateKey));
            KeyFactory keyf = KeyFactory.getInstance("RSA");
            PrivateKey priKey = keyf.generatePrivate(priPKCS8);
            
            Signature signature = Signature.getInstance(SIGN_ALGORITHMS);
            signature.initSign(priKey);
            signature.update(content.getBytes(encode));
            
            byte[] signed = signature.sign();
            return Base64Utils.encodeToString(signed);
        } catch (Exception e) {
            e.printStackTrace();
            throw new Exception();
        }
    }


    /**
     * RSA验签名检查
     * 
     * @param content
     *            待签名数据
     * @param sign
     *            签名值
     * @param publicKey
     *            分配给开发商公钥
     * @param encode
     *            字符集编码
     * @return 布尔值
     * @throws Exception 
     */
    public static boolean doCheck(String content, String sign, String publicKey, String encode) throws Exception {
        try {
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            byte[] encodedKey = Base64Utils.decodeFromString(publicKey);
            PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));
            Signature signature = Signature.getInstance(SIGN_ALGORITHMS);
            signature.initVerify(pubKey);
            signature.update(content.getBytes(encode));
            boolean bverify = signature.verify(Base64Utils.decodeFromString(sign));
            return bverify;
        } catch (Exception e) {
            throw new Exception();
        }
    }
}
